Control of RNA methylation by growth signals through the mTORC1 pathway

摘要 雷帕霉素复合体1(MTORC1)的机制靶点是感知和整合多种环境信号 控制消耗能量和营养的生物合成过程，如蛋白质、脂肪和核苷酸 综合。MTORC1通过翻译后和转录机制刺激合成代谢细胞的生长 导致增加大分子合成是增加细胞生物量启动细胞的先决条件 成长和分裂。在许多疾病中，mTORC1信号的突出加强了 考虑将mTORC1信号转导靶向几种疾病，包括神经退行性疾病，糖尿病， 肿瘤综合征和衰老。然而，直接的mTORC1靶向治疗，在概念上和临床前 这是一个有希望的靶点，在人类患者身上只显示出有限的疗效。因此，更好地理解 MTORC1下游的生物学和更有效和特异的治疗策略的开发 MTORC1驱动的疾病的治疗是必要的。为了实现伴随着生物合成的需求 为了促进细胞的增殖，细胞必须增加从环境中运输营养物质。葡萄糖、乳酸和谷氨酰胺 是促进哺乳动物细胞生物合成和存活的主要营养物质。正在出现的一个方面 在衰老和增殖性疾病中的营养利用包括饮食蛋氨酸限制的作用，这是 最近在肥胖、代谢综合征和癌症的背景下进行了研究。蛋氨酸是一种必需的 在一系列被称为蛋氨酸的代谢反应中分解和循环的氨基酸 周而复始。甲硫氨酸和三磷酸腺苷通过转化为通用的甲基供体S-腺苷蛋氨酸 蛋氨酸腺苷转移酶2α(MAT2A)酶。根据这项建议，我们建议研究 MTORC_1信号转导对S-腺苷蛋氨酸合成及其甲基化的影响 支持合成代谢的过程。我们已经证实mTORC1刺激SAM合成。 通过c-myc直接转录控制MAT2A的表达，从而影响细胞的各种环境。我们建议 评估mTORC1信号对多种人类细胞(特异性Aim1)合成SAM的影响。将要 确定mTORC1信号促进RNA甲基化的机制，特别是N6- 甲基腺苷(M6A)标记。我们将在对照中确定m6A对mTORC1下游RNA的作用 细胞生长(特异性AIM2)。此外，我们将确定mTORC1-MAT2A轴在 肿瘤生长和由此机制衍生的潜在治疗策略(特异性Aim3)。因此， 这项提议的总体目标是破译mTORC1控制RNA的分子机制 正常和病理环境中的甲基化。我们预期拟议的研究将产生新的见解。 探讨SAM水平如何改变合成代谢，并将发现干扰mTORC1驱动的治疗靶点 疾病。

SUMMARY The mechanistic target of rapamycin complex 1 (mTORC1) senses and integrates diverse environmental signals to control energy and nutrient-consuming biosynthetic processes, such as protein, lipid, and nucleotide synthesis. mTORC1 stimulates anabolic cell growth through posttranslational and transcriptional mechanisms leading to increased macromolecule synthesis a prerequisite to augment cellular biomass priming cells for growth and division. In many diseases, the prominence of mTORC1 signaling reinforces the importance of considering targeting mTORC1 signaling in several diseases including neurodegenerative disorders, diabetes, tumor syndromes, and aging. However, direct mTORC1 targeted therapies, being conceptually and preclinically a promising target, displayed only limited efficacy in human patients. Therefore, a better understanding of the biology downstream of mTORC1 and the development of more effective and specific therapeutic strategies in the treatment of mTORC1-driven diseases are needed. To achieve the biosynthetic demands accompanying proliferation, cells must increase the transport of nutrients from the environment. Glucose, lactate, and glutamine are the principal nutrients that promote biosynthesis and survival in mammalian cells. An emerging aspect of nutrient utilization in aging and proliferative diseases includes the role of dietary methionine restriction, which was recently explored in the context of obesity, metabolic syndrome, and cancer. Methionine is an essential amino acid that is catabolized and recycled in a sequence of metabolic reactions designated as the methionine cycle. Methionine and ATP are converted into the universal methyl donor S-adenosylmethionine (SAM) via the methionine adenosyltransferase 2 alpha (MAT2A) enzyme. Under this proposal, we propose to study the influence of mTORC1 signaling on S-adenosylmethionine (SAM) synthesis and the subsequent methylation processes supporting anabolic metabolism. We have identified that mTORC1 stimulates SAM synthesis in various cell settings through direct transcriptional control of MAT2A expression by c-MYC. We propose to evaluate the influence of mTORC1 signaling on SAM synthesis in a variety of human cells (Specific Aim1). Will identify the mechanisms by which mTORC1 signaling promotes RNA methylation, particularly the N6- methyladenosine (m6A) mark. We will determine the role of m6A on RNA downstream of mTORC1 in the control of cell growth (Specific Aim2). Furthermore, we will determine the implication of the mTORC1-MAT2A axis on tumor growth and the potential therapeutic strategy derived from this mechanism (Specific Aim3). Thus, the overall goal of this proposal is to decipher the molecular mechanisms by which mTORC1 controls RNA methylation in normal and pathological settings. We anticipate that the proposed studies will yield new insights into how SAM levels alter anabolic metabolism and will uncover therapeutic targets to perturb mTORC1-driven diseases.